Laser welding is well known in the art. Systems that monitor a laser welding process and provide an evaluation of the process are also known in the art.
U.S. Pat. No. 4,663,513 to T. Webber discloses use of a laser to deliver energy to a workpiece along a process path for welding purposes. Plasma is produced at a beam delivery point along the process path. A radiation detector is used to detect infrared radiation at a point behind and apart from the location of the beam delivery point. The radiation detector provides an analog temperature signal having a value which varies over time with changes in intensity of the received infrared radiation. The analog temperature signal is compared against a window range of acceptable temperatures. If the temperature signal is not within the window range, a fault signal is produced.
The U.S. Pat. No. 3,262,006 to Sciaky et al. discloses a welding control system having a light sensitive probe and fiber-optics to conduct illumination from an area adjacent a weld to a photo transducer disposed at a remote location. Also, an ultraviolet filter may be employed in the system to see through the flame portion of the weld arc to the inner plasma portion. The U.S. Pat. No. '006 system maintains an electrode at a substantially constant distance from the workpiece.
The U.S. Pat. No. 4,446,354 to Kearney discloses an opto-electronic weld monitoring system employing fiber-optic delivery of incident radiation to a plurality of photo-detectors. The photo-detectors evaluate the weld by separating the received radiation into spectral bands. The output of each photo-detector is compared with a known reference value. A significant deviation in the comparison indicates a fault.